AOI (Automated Optical Inspection) is an effective inspection method for industrial automation. It uses machine vision as the standard inspection technology. It is widely used in LCD/TFT, transistor and PCB industrial processes, and can be extended to security systems in people's livelihood. The automated optical inspection is a common representative method in industrial processes, which utilizes an optical manner to obtain the surface state of an object to be inspected and inspects defects such as a foreign object or an abnormal pattern through image processing. Because it is non-contact inspection, semi-finished products can be inspected in intermediate processes. When an automated inspection is performed, the machine automatically scans an inspection object through a camera, collects an image thereof, compares the solder joints tested to qualified parameters in a database, finds out, after image processing, defects on the object, and displays/denotes the defects through a display or an automated sign for maintaining by the maintenance personnel.